Dynamic submicroscopic signaling zones revealed by pair correlation tracking and localization microscopy

Area of Science:

• Cell biology
• Biophysics
• Immunology

Background:

• Understanding the spatiotemporal organization of signaling complexes in plasma membrane nanodomains is crucial but challenging.
• The type I interferon (IFN) receptor plays a key role in cellular signaling pathways.

Purpose of the Study:

• To investigate the dynamic assembly of signaling complexes at the plasma membrane using super-resolution microscopy.
• To probe ligand binding, receptor behavior, and effector recruitment in live cells.

Main Methods:

• Application of super-resolution image correlation based on tracking and localization microscopy (TALM).
• Labeling of ligand and type I IFN receptor with monofunctional quantum dots for long-term, high-resolution tracking.
• Dual-color TALM and pair correlation analyses based on time-lapse TALM images (pcTALM) to visualize protein interactions.

Main Results:

• Visualized transient confinement, ligand binding, and effector recruitment of the type I IFN receptor.
• Identified complex assembly within dynamic submicroscopic zones using pcTALM.
• Observed the recruitment of signal transducer and activator of transcription 2 (STAT2) into these signaling zones.

Conclusions:

• Confined diffusion zones in the plasma membrane act as transient platforms for signaling complex assembly.
• This mechanism is critical for initiating downstream signaling events, such as those initiated by type I interferons.